Fiber optic cable with electrical connectors at both ends

ABSTRACT

A fiber optic cable is disclosed, a fiber optic cable containing multiple optical fibers within an enclosure, where the fibers are divided into two groups, the first group of fibers being arrayed together and the second group being free fibers. The arrayed fibers are used to carry signals that are desired to be maintained in synchronization with each other, while the free fibers are used to carry signals whose synchronization with other signals is not important. In one example, four optical fibers form a linear array, and two free optical fibers are arranged on two sides of the linear array.

BACKGROUND OF THE INVENTION

This invention relates to a data transmission cable using optical fibersand having electrical connectors at both ends, and related fabricationmethods.

SUMMARY OF THE INVENTION

The present invention is directed to a connecting device for a fiberoptic cable for converting electrical signals and optical signals toeach other, and a cable device having a fiber optic cable and suchconnecting devices at both ends.

Additional features and advantages of the invention will be set forth inthe descriptions that follow and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims thereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, the presentinvention provides a fiber optic cable containing multiple opticalfibers within an enclosure, where the fibers are divided into twogroups, the first group of fibers being arrayed together and the secondgroup being free fibers. The arrayed fibers are used to carry signalsthat are desired to be maintained in synchronization with each other,while the free fibers are used to carry signals whose synchronizationwith other signals is not important.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a connecting device for a fiber opticcable according to an embodiment of the present invention.

FIG. 2 schematically illustrates a fiber optic cable device having twoconnecting devices at its ends according to an embodiment of the presentinvention.

FIGS. 3A-3C illustrate exemplary exterior views the connecting device ofembodiments of the present invention.

FIG. 4 is a cross-sectional view of a fiber optic cable according toanother embodiment of the present invention.

FIGS. 5A, 5B and 5C illustrate previously disclosed connecting devices.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Chinese utility model patent application No. 201020599351.6, filed Nov.4, 2010 and granted on Jul. 20, 2011 as CN 201903673 U (hereinafter “theCN '673 patent”), is herein incorporated by reference in its entirety.FIGS. 1, 5 a and 8 f of the CN '673 patent are reproduced as FIGS. 5A,5B and 5C of the present application. The disclosure of the CN '673patent is summarized briefly below.

The CN '673 patent describes a connecting device for use with an opticalfiber cable for data transmission. As shown in FIGS. 5A, 5B and 5C(FIGS. 1, 5 a and 8 f of the CN '673 patent), one end of the connectingdevice is provided with an electrical connector 1 which complies with astandard format such as HDMI (High Definition Multimedia Interface), VGA(Video Graphics Array), DP (DisplayPort), DVI (Digital VisualInterface), etc. The other end of the connecting device accommodates anoptical fiber cable or optical fiber bundle. Various components arecontained in a housing of the connecting device and mounted on a circuitboard 2, and function to convert electrical signals from the electricalconnector 1 into optical signals transmitted onto the optical fibers 3,and to convert optical signals from the optical fibers 3 into electricalsignals transmitted onto the electrical connector 1. These internalcomponents include, in the example shown in FIGS. 5A and 5C, a chipelectrically connected to the electrical connector 1, for processingelectrical signals; an optical transceiver block (not shown in FIGS. 5Aand 5C) having multiple individual optical transceivers, electricallyconnected to the chip, for converting optical signals to electricalsignals and vice versa; an optical component positioning block 4, forpositioning the optical transceivers to the circuit board; a lens block5, positioned on the optical component positioning block 4, for focusingand reflecting light signals between the optical transceivers and theoptical fibers; and an optical fiber positioning block 6, forpositioning the optical fibers to the lens block 5. FIG. 5A shows astate where the optical fiber positioning block 6 is not yet alignedwith the lens block 5; FIG. 5C shows a state where the components areassembled an placed inside the housing but the top cover of the housingis still open. The example shown in FIG. 5B is similar to the exampleshown in FIG. 5A except that the multiple individual opticaltransceivers are directly mounted on the optical component positioningblock 54 which faces the optical fiber positioning block 56, and thelens block is omitted.

Embodiments of the present invention improves the connecting devicedescribed in the CN '673 patent by separating the various internalcomponents, which are contained in a single housing in the CN '673patent, into two groups and arrange them in two separate housings. Anembodiment of the present invention is schematically illustrated in FIG.1 of the present disclosure.

As shown in FIG. 1, the connecting device 100 includes a first part 110and a second part 120 adapted to be electrically and mechanicallyconnected to each other. The first part 110 has a first electricalconnector 111 and a second electrical connector 112 disposed on ahousing 113. The first connector 111, which may be referred to as theexternal connector of the connecting device 100, is preferably one thatcomplies with a standard format such as HDMI, VGA, DP, DVI, etc.,similar to the electrical connector 1 of the previously disclosedconnector device shown in FIGS. 5A-5C. Contained inside the housing 113are one or more electrical components such as a chip 114 for processingelectrical signals. The chip 114 is electrically connected to the firstelectrical connector 111 by a first set of wires 115, and to the secondelectrical connector 112 by a second set of wires 116. The chip and thewires may be formed on a circuit board enclosed in the housing 113.

The second part 120 of the connecting device 100 has a first electricalconnector 121 disposed on a housing 122. The first electrical connector121 is designed to electrically and mechanically connect with the secondelectrical connector 112 of the first part 110. The connectors 112 and121 are not required to comply with any commonly recognized standard, solong as they can mate with each other. Contained inside the housing 122are an optical transceiver block 123 including a plurality of opticaltransceivers (such as laser diodes (LD) and/or photo detectors (PD)),and an optical fiber positioning block 124 for receiving and positioninga set of optical fibers 125 from an optical fiber cable 127. The opticaltransceivers, which are electrically connected to the first electricalconnector 121 by a set of wires 126, convert optical signals toelectrical signals and vice versa. The optical fiber positioning block124 positions the end of the optical fibers 125 relative to the opticaltransceivers such that light signals are transmitted between the opticaltransceivers and the optical fibers. Either the optical transceiverblock 123 or the optical fiber positioning block 124 or both may includeoptical elements such as lenses, reflectors, etc. to direct the lightsignals. Preferably, the optical fibers 125 include multiple fibers fortransmitting various signals. In one example, six optical fibers areused for transmitting HDMI signals, four of which carry the Tc, T0, T1and T2 signals, and two carry the SCL, SDA, HPD, CEC, and ARC signals ina multiplexed manner. The chip 114 carries out the necessarymultiplexing/demultiplexing functions.

The optical transceiver block 123 and the optical fiber positioningblock 124 may have any suitable structures. In one example, the opticaltransceiver block 123 has a structure similar to the combined structureof the an optical component positioning block 4, the a lens block 5, andthe optical transceiver block shown and described in FIGS. 5A and 5C. Inanother example, the optical transceiver block 123 has a structuresimilar to the optical component positioning block 54 shown anddescribed in FIG. 5B. In one embodiment, the optical fiber positioningblock 124 has a structure similar to the optical fiber positioning block6 shown and described in FIG. 5A, or the optical fiber positioning block56 shown and described in FIG. 5B. Other suitable structures may be usedas well.

In the previously disclosed structures shown in FIGS. 5A-5C, the opticaltransceivers are electrically connected to the chip by wires. In effect,the embodiment shown in FIG. 1 of the instant disclosure divides thecomponents of shown in FIGS. 5A-5C into two groups at the location ofthese wires, and locate the two groups of components in two separatehousings with appropriate electrical connector to connect the two.Preferably, in embodiments of the present invention, most or allelectrical signal processing circuitry, including generating drivesignals for the laser in the optical transceiver, is located in thefirst housing, so the second housing contains very little or noelectrical signal processing circuitry, enabling the size of the secondhousing to be minimized. All components related to transmitting andprocessing of optical signals are located in the second housing. Theconnection between the two housings only involves electrical connection.

In the embodiment illustrated in FIG. 1, the first electrical connector111 for the first part 110 is a male connector, but it may also be amale connector. Further, the second electrical connector 112 of thefirst part 110 is a female connector and the first electrical connector121 of the second part 120 is a female connector, but the reversestructure may be used.

FIG. 2 illustrate an embodiment of the present invention which is acable device 101 having an optical fiber cable 127 and two connectingdevices 100, 100A at its two ends. Typically, the two connecting devices100, 100A are not identical because one end of the cable device 101 isprimarily a transmitting end and the other end is primarily a receivingend (even though different signals may be transmitted in differentdirections simultaneously). In the example shown in FIG. 2, eachconnecting device 100, 100A is formed of two parts as described above.Alternatively, one connecting device (e.g. 100) may be formed of twoparts while the other (e.g. 100A) may be formed of a single part similarto that of the previously disclosed connector device shown in FIGS.5A-5C.

The external connectors 111 and 111A and the electronic componentswithin the connecting devices 100 and 100A may be the same or different.When they are different, the cable device may function as an adaptor orconverter, which converts electrical signals complying with one standardto electrical signals complying with a different standard. When the twoexternal connectors 111 and 111A are the same or comply with the samestandard, the cable device may function as an extender or connectorcable to connect two external devices located remotely with respect toeach other. For example, one practical application of the cable device101 is an HDMI to HDMI fiber optic connector for connecting a TV at oneend (the receiving end) and a DVD player or another source device at theother end (the transmitting end).

In one particular example, the cable device 101 is an adaptor with anApple Lightening connector, or an Apple 30-pin connector, or an MHL(Mobile High-Definition Link) connector at one end, and an HDMIconnector at the other end. Such a cable will allow an Apple device suchas iPad™, iPhone™ and iPod™ or other mobile devices to be connected toan HDTV or other HDMI-compatible display device, so that the images seenon the mobile device can be displayed on the screen of the HDTV or theother HDMI-compatible device. Lightening and 30-pin are two types ofconnectors used by various versions of Apple's iPad™, iPhone™ and iPod™devices. MHL is a standard mobile audio/video interface. The signalconversion schemes between Lightening, 30-pin or MHL and HDMI are known,as Lighting connector to HDMI adaptors, 30-pin connector to HDMIadaptors and MHL to HDMI adaptors are known and commercially availablefrom various sources, even though these adaptors use electrical ratherthan optical cables for signal transmission. In such an adaptor cable,either the Lightening or 30-pin connector, or the HDMI connector, orboth, may be made as a two-part structure by implementing embodiments ofthe present invention.

Referring back to FIG. 1, forming the connecting device 100 in two parts110 and 120 offers many advantages. First, by locating the electricalcomponents 114 and the external connector 111 in a detachable first part110, the second part 120 contains very little or no electrical signalprocessing circuitry; thus, the size of the second part 120 can bereduced, so that it can be much smaller than the previously disclosedconnector device shown in FIGS. 5A-5C. For example, the size of thesecond part 120 can be smaller than 0.35 by 0.25 by 0.75 inches. Whenconnecting two external devices located remotely to each other, thecable device 101 often needs to be passed through narrow passages in abuilding, such as conduit inside walls of the building. To pass througha pipe having a limited size, the first part 110 can be detached, andthe second part 120 with the cable 127 can be passed through the pipemore easily. For example, many older residential buildings have pipes of0.5 inches in diameter with 90 degree turns. It would have been verydifficult or impossible to pass the previously disclosed connector shownin FIGS. 5A-5C through such conduit, whereas the second part 120 of theembodiments of this invention can easily pass through such conduit.After the second part 120 is passed through the conduit, the first part110 is attached to the second part 120 and the connecting device 100 isready to be connected to an external device.

Second, in the embodiment of the present invention shown in FIG. 1, thefirst part 110 of the connecting device 100 contains only electricalcomponents and no optical components. Therefore, it can be fabricatedmore easily and reliably using mature technologies, which reduces thecost of the overall cable device.

Further, because the connection (i.e. connectors 112 and 121) betweenthe first part 110 and second part 120 is s pure electrical connectionwithout involving any optical signals, the connection is not prone toproblems relating to connecting two optical fibers.

It should be noted that FIGS. 1 and 2 of the instant disclosure are onlyintended as schematic illustrations; they do not necessarily representthe actual shape, size or spatial arrangements of the variouscomponents. For example, while the fibers 125 are shown in FIG. 1 asbeing fanned out, they are not limited to this configuration, and theymay go straight out to the LD or PD.

FIGS. 3A-3C illustrates exemplary exterior views of the connectingdevice 100 according one particular embodiment of the present invention.FIG. 3A shows the two parts 110 and 120 being uncoupled from each other,and FIG. 3B shows the two parts being coupled to each other. FIG. 3Cillustrates the front, side and top views of the connecting device 100.

FIG. 4 is a cross-sectional view illustrating a fiber optic cableaccording to an embodiment of the present invention, which can be usedas the cable 127 in FIGS. 1 and 2. As mentioned earlier, HDMI signalsmay be transmitted via six optical fibers, with four fibers carrying theTc, T0, T1 and T2 signals and two fibers carrying the various othersignals (SCL, SDA, HPD, CEC, and ARC). In the embodiment shown in FIG.4, the four fibers 201A to 201D that carry the Tc, T0, T1 and T2 signalsare formed into a fiber array by aligning the four fibers together sideby side with a suitable adhesive material 202. The two other fibers 201Eand 201F which carry the other data are not formed into the same fiberarray as the first four fibers. In other words, each of fibers 201E and201F is free and not adhered to any other fibers, and its location withrespect to the other fibers is not fixed and may shift as the cable ismoved. The six fibers 201A to 201F are enclosed by a protectingenclosure 203 to form the fiber optic cable.

The fiber arrangements described above has certain advantages. Becausethe Tc, T0, T1 and T2 signals are required to be synchronized as much aspossible, the four fibers carrying these signals should be formed intoan array so that the changes in their relative lengths are minimizedwhen the cable bends or is coiled up. When multiple fibers are formedinto an array, such as shown in FIG. 4 (four fibers 201A to 201D formingan array), the array can be easily bend in one direction but not in theother (perpendicular) direction. In the example shown in FIG. 4, whenthe fibers 201A-201D extend perpendicular to the plane of the paper, thearray can be easily bent in the up-down direction, but not theleft-right direction due to the four fibers being adhered to each otherside by side in the left-right direction. Thus, reducing the size of thefiber array will make the cable easier to handle. In the embodimentshown in FIG. 4, only four fibers are arrayed together, and the othertwo fibers 201E and 201F can shift their positions within the enclosure203 as the cable 200 is bent. The two free fibers can in fact move andfill in the “void” within the enclosure 203 which helps to reduce thestrain on the cable. This arrangement balances the need to have the fourfibers carrying the Tc, T0, T1 and T2 signals arrayed to maintain signalsynchronization, and the need to make the cable easier to handle. If, onthe other hand, all six fibers are formed into an array, the resultingarray will be larger, making the cable more difficult to bend in theleft-right direction and therefore harder to handle.

In the example illustrated in FIG. 4, six fibers are shown with fourbeing arrayed together. This is suitable for transmitting HDMI signals.Depending on the requirements of the signals being transmitted, adifferent number of fibers may be arrayed and a different number offibers may be free. The general principle is that only fibers carryingsynchronized signals should be arrayed and the other fibers should befree.

It will be apparent to those skilled in the art that variousmodification and variations can be made in the connecting device andrelated methods of the present invention without departing from thespirit or scope of the invention. Thus, it is intended that the presentinvention cover modifications and variations that come within the scopeof the appended claims and their equivalents.

What is claimed is:
 1. A fiber optic cable comprising: a plurality ofoptical fibers; and an enclosure the encloses the plurality of opticalfibers, where the plurality of optical fibers includes two groups ofoptical fibers, the first group of optical fibers being arrayed togetherand the second group of optical fibers being free fibers.
 2. The fiberoptic cable of claim 1, wherein the first group includes four opticalfibers forming a linear array, and the second group includes two opticalfibers arranged on two sides of the linear array.
 3. The fiber opticcable of claim 1, wherein the first group of optical fibers are adheredto each other by an adhesive material.